Again, I was asked:

Why some members of America Needs Fatima practice perfect chastity...

Were it not better for members of America Needs Fatima (TFP) to get married instead of remaining single, fully dedicated to the mission?

Then, this quote from the encyclical of Pope Pius XII called "Sacra Virginitas" came to my attention.

I think it answers the question quite well: "And while this perfect chastity is the subject of one of the three vows which constitute the religious state, [9] and is also required by the Latin Church of clerics in major orders [10] and demanded from members of Secular Institutes, [11] it also flourishes among many who are lay people in the full sense: men and women who are not constituted in a public state of perfection and yet by private promise or vow completely abstain from marriage and sexual pleasures, in order to serve their neighbor more freely and to be united with God more easily and more closely. 7. To all of these beloved sons and daughters who in any way have consecrated their bodies and souls to God, We address Ourselves, and exhort them earnestly to strengthen their holy resolution and be faithful to it. (my emphasis)